1. Automotive Technology Principles, Diagnosis, and Service
Sixth Edition
Chapter 55
Charging System Diagnosis and Service
Copyright © 2018, 2015, 2011 Pearson Education, Inc. All Rights Reserved

2. LEARNING OBJECTIVES (1 of 2)
55.1 Discuss the various methods to test the charging system Describe how to inspect and adjust the drive belts Discuss the alternator output test and minimum required output.

3. LEARNING OBJECTIVES (2 of 2)
55.4 Explain how to remove, disassemble, reassemble, and install an alternator and test its component parts Describe remanufactured alternators This chapter will help prepare for the ASE Electrical/Electronic Systems (A6) certification test content area “D” (Charging System Diagnosis and Repair).

4. CHARGING SYSTEM TESTING AND SERVICE (1 OF 2)
Battery State Of Charge
The battery must be at least 75% charged before testing the alternator and the charging system.
Charging Voltage Test
Set digital multimeter to DC Volts
Connect the meter leads to the battery
Operate the engine at 2000 RPM
Specifications: Volts

5. CHARGING SYSTEM TESTING AND SERVICE (2 OF 2)
Scan Testing the Charging System
Many vehicles use a computer-controlled charging system can be diagnosed using a scan tool.
The charging voltage can be monitored
The field circuit can be controlled

6. Figure 55.1 The digital multimeter should be set to read DC volts, with the red lead connected to the positive (+) battery terminal and the black meter lead connected to the negative (-) battery terminal

7. Figure 55.2 A scan tool can be used to diagnose charging system problems

8. Tech Tip 

9. Figure 55.3 Before replacing an alternator, the wise technician checks that battery voltage is present at the output and battery voltage sense terminals.

10. DRIVE BELT INSPECTION AND ADJUSTMENT
Belt Visual Inspection
Replace any serpentine belt that has more than three cracks in any one rib that appears in a 3-inch span.
Belt Tension Measurement
Belt tension gauge
Marks on a tensioner
Torque wrench readings
Deflection
Overrunning Clutch
Check for proper operation

11. Figure 55.4 (a) This accessory drive belt is worn and requires replacement. Newer belts are made from ethylene propylene diene monomer (EPDM). This rubber does not crack like older belts and may not show wear, even though the ribs do wear and can cause slippage

12. Figure 55. 4 (b) A belt wear gauge being used to check a belt
Figure 55.4 (b) A belt wear gauge being used to check a belt. It should fit tightly but if it is able to be moved side to side, then the belt is worn and should be replaced

13. Chart 55-1 Typical belt tension for various widths of belts
Chart 55-1 Typical belt tension for various widths of belts. Tension is the force needed to depress the belt as displayed on a belt tension gauge.

14. Figure 55.5 Check service information for the exact marks where the tensioner should be located for proper belt tension

15. Figure 55.6 This overrunning alternator dampener (OAD) is longer than an overrunning alternator pulley (OAP) because it contains a dampener spring, as well as a one-way clutch. Be sure to check that it locks in one direction

16. Figure 55.7 A special tool is needed to remove and install overrunning alternator pulleys or dampeners

17. What are the four ways to measure belt tension?
QUESTION 1: ?
What are the four ways to measure belt tension?

18. ANSWER 1:
Belt tension gauge, marks on a tensioner, torque wrench readings, deflection.

19. AC RIPPLE VOLTAGE CHECK
Principles
A good alternator should produce very little AC voltage or current output.
Testing AC Ripple Voltage
Set the digital meter to read AC volts.
Start the engine and operate it at 2,000 RPM
Connect the voltmeter leads to the battery terminals.
Turn on the headlights
The voltmeter should read less than 400 millivolts (0.4 volt) AC.

20. Figure 55.8 Testing AC ripple at the output terminal of the alternator is more accurate than testing at the battery due to the resistance of the wiring between the alternator and the battery.

21. TECH TIP

22. Figure 55.9 Charging system voltage can be easily checked at the lighter plug by connecting a lighter plug to the voltmeter through a double banana plug

23. TESTING AC RIPPLE CURRENT
A mini clamp-on meter capable of measuring AC amperes can be used to check the alternator.
Start the engine and turn on the lights
Using a mini clamp-on digital multimeter, place the clamp around either cables
Switch the meter to read AC amperes and record the reading
The results should be within 10% of the specified alternator rating

24. Figure A mini clamp-on meter can be used to measure alternator output, as shown here (105.2 amperes). Then the meter can be used to check AC ripple by selecting AC amps on the rotary dial. AC ripple should be less than 10% of the DC output

25. What is the purpose of the AC ripple test?
QUESTION 2: ?
What is the purpose of the AC ripple test?

26. To ensure the alternator is properly converting the AC to DC.
ANSWER 2:
To ensure the alternator is properly converting the AC to DC.

27. CHARGING SYSTEM VOLTAGE DROP TESTING
Voltage Drop Test Procedure
Start the engine and run it at 2000 RPM
Turn on the headlights to create an electrical load
Using any voltmeter set to read DC volts
Connect the positive test lead (red) to the output terminal of the alternator.
Attach the negative test lead (black) to the positive post of the battery.
If there is less than a 0.4 volt (400 millivolts) reading, then all wiring and connections are satisfactory

28. Figure 55.11 Voltmeter hookup to test the voltage drop of the charging circuit

29. ALTERNATOR OUTPUT TEST
Carbon Pile Test Procedure
Connect the starting and charging test leads according to the manufacturer’s instructions
Turn off all electrical accessories
Start the engine and operate it at 2,000 RPM
Turn the load increase control slowly to obtain the highest reading on the ammeter scale
Do not allow the voltage to drop below 12.6 volts.
Compare the output reading to factory specifications

30. Figure A typical tester used to test batteries as well as the cranking and charging system. Always follow the operating instructions

31. MINIMUM REQUIRED ALTERNATOR OUTPUT
Connect the ammeter according to the instructions
Start the engine and operate to about 2,000 RPM
Turn on any accessories that may be used continuously (lights, wipers, rear defogger, etc.)
Observe the ammeter. The current indicated is the electrical load that the alternator is able to exceed to keep the battery fully charged.

32. Figure The best place to install a charging system tester amp probe is around the alternator output terminal wire, as shown in the figure

33. What is the purpose of the alternator output test?
QUESTION 3: ?
What is the purpose of the alternator output test?

34. To determine the maximum output capability of the alternator.
ANSWER 3:
To determine the maximum output capability of the alternator.

35. ALTERNATOR REMOVAL
A typical removal procedure includes the following steps.
Disconnect the negative (-) terminal from the battery
Remove the accessory drive belt
Remove electrical wiring, fasteners, spacers, and brackets
Remove the alternator

36. Figure Replacing an alternator is not always as easy as it is from a Buick with a 3800 V-6, where the alternator is easy to access. Many alternators are difficult to access and require the removal of other components

37. FREQUENTLY ASKED QUESTION

38. Figure 55. 15 Explanation of clock positions
Figure Explanation of clock positions. Because the four through bolts are equally spaced, it is possible for an alternator to be installed in one of four different clock positions.

39. ALTERNATOR DISASSEMBLY (1 OF 2)
Disassembly Procedure
Mark the case to ensure proper reassembly
Remove the through bolts and separate the two halves
Remove the rectifier and voltage regulator
Rotor Testing
Measure the resistance between the slip rings using an ohmmeter
If a rotor is found to be bad it must be replaced

40. ALTERNATOR DISASSEMBLY (2 OF 2)
Stator Testing
The stator must be disconnected before testing
There should be low resistance at all three stator leads
If the stator is shorted-to-ground and must be repaired or replaced.
Testing the Diode Trio
The multimeter should indicate 0.5 to 0.7 volt (500 to 700 millivolts) one way and OL (overlimit) after reversing the test leads and touching all three connectors of the diode trio.

41. Figure 55.16 Testing an alternator rotor using an ohmmeter

42. Figure If the ohmmeter reads infinity between any two of the three stator windings, the stator is open and, therefore, defective.

43. Figure A diode trio can be tested using an analog (needle-type) ohmmeter or a digital meter set to “diode check”

44. TESTING THE RECIFIER
The rectifier(s) (diodes) should be tested using a multimeter (DMM) that is set to “diode check” position.
A good diode should have high resistance (OL) one way (reverse bias) and low voltage drop of 0.5 to 0.7 volt (500 to 700 millivolts) the other way (forward bias).

45. Figure 55.19 A typical rectifier bridge that contains all six diodes in one replaceable assembly

46. REASSEMBLING THE ALTERNATOR
After testing or servicing, the alternator rectifier(s), regulator, stator, and brush holder must be reassembled using the following steps.
Insert a wire through the holes in the brush holder to hold the brushes against the springs.
Install the rotor and front-end frame in proper alignment with the mark made on the outside of the alternator housing.
Alternators should be tested on a bench tester

47. Figure 55. 20 A brush holder assembly with new brushes installed
Figure A brush holder assembly with new brushes installed. The holes in the brushes are used to hold the brushes up in the holder when it is installed in the alternator.

48. FREQUENTLY ASKED QUESTION

49. Figure An example of a rotor assembly that, if tested to be within specification, is suitable to be reinstalled after the slip rings have been cleaned

50. REMANUFACTURERED ALTERNATORS
Remanufactured or rebuilt alternators are totally disassembled and rebuilt.
Used alternators are returned and used as cores.
Every alternator is tested prior to shipping

51. ALTERNATOR INSTALLATION
Verify that the replacement alternator is correct
Install the alternator wiring on the alternator and install the alternator
Install and properly tension the drive belt
Reconnect the negative battery cable
Start the engine and verify proper charging circuit operation

52. ALTERNATOR OVERHAUL

53. 1. Before the alternator is disassembled, it is spin tested and connected to a scope to check for possible defective components.

54. 2. The scope pattern shows that the voltage output is far from being a normal pattern. This pattern indicates serious faults in the rectifier diodes.

55. 3. The first step is to remove the drive pulley
3. The first step is to remove the drive pulley. This rebuilder is using an electric impact wrench to accomplish the task.

56. 4. Carefully inspect the drive galley for damage of embedded rubber from the drive belt. The slightest fault can cause a vibration, noise, or possible damage to the alternator.

57. 5. Remove the external fan (if equipped) and then the spacers, as shown.

58. 6. Next pop off the plastic cover (shield) covering the stator/rectifier connection.

59. 7. After the cover has been removed, the stator connections to the rectifier can be seen.

60. 8. Using a diagonal cutter, cut the weld to separate the stator from the rectifier.

61. 9. Before separating the halves of the case, this technician uses a punch to mark both halves.

62. 10. After the case has been marked, the through bolts are removed.

63. 11. The drive-end (DE) housing and the stator are being separated from the rear (slip-ring-end) housing.

64. 12. The stator is checked by visual inspection for discoloration or other physical damage, and then checked with an ohmmeter to see if the windings are shorted-to-ground.

65. 13. The front bearing is removed from the drive-end housing using a press.

66. 14. A view of the slip-ring-end (SRE) housing showing the black plastic shield, which helps direct air flow across the rectifier.

67. 15. A punch is used to dislodge the plastic shield retaining clips.

68. 16. After the shield has been removed, the rectifier, regulator, and brush holder assembly can be removed by removing the retaining screws.

69. 17. The heat transfer grease is visible when the rectifier assembly is lifted out of the rear housing.

70. 18. The parts are placed into a tumbler where ceramic stones and a water-based solvent are used to clean the parts.

71. 19. This rebuilder is painting the housing using a high-quality industrial grade spray paint to make the rebuilt alternator look like new.

72. 20. The slip rings on the rotor are being machined on a lathe.

73. 21. The rotor is being tested using an ohmmeter
21. The rotor is being tested using an ohmmeter. The specifications for the resistance between the slip rings on the CS-130 are 2.2 to 3.5 ohms.

74. 22. The rotor is also tested between the slip ring and the rotor shaft
22. The rotor is also tested between the slip ring and the rotor shaft. This reading should be infinity.

75. 23. A new rectifier. This replacement unit is significantly different than the original but is designed to replace the original unit and meets the original factory specifications.

76. 24. Silicone heat transfer compound is applied to the heat sink of the new rectifier.

77. 25. Replacement brushes and springs are assembled into the brush holder.

78. 26. The brushes are pushed into the brush holder and retained by a straight wire, which extends through the rear housing of the alternator. This wire is then pulled out when the unit is assembled.

79. 27. Here is what the CS alternator looks like after installing the new brush holder assembly, rectifier bridge, and voltage regulator.

80. 28. The junction between the rectifier bridge and the voltage regulator is soldered.

81. 29. The plastic deflector shield is snapped back into location using a blunt chisel and a hammer. This shield directs the airflow from the fan over the rectifier bridge and voltage regulator.

82. 30. Before the stator windings can be soldered to the rectifier bridge, the varnish insulation is removed from the ends of the leads.

83. 31. After the stator has been inserted into the rear housing the stator leads are soldered to the copper lugs of the rectifier bridge.

84. 32. New bearings are installed
32. New bearings are installed. A spacer is placed between the bearing and the slip rings to help prevent the possibility that the bearing could move on the shaft and short against the slip ring.

85. 33. The slip-ring-end housing is aligned with the marks made during disassembly and is pressed into the drive-end housing.

86. 34. The retaining bolts, which are threaded into the drive-end housing from the back of the alternator, are installed.

87. 35. The external fan and drive pulley are installed and the retaining nut is tightened on the rotor shaft.

88. 36. The scope pattern shows that the diodes and stator are functioning correctly and voltage check indicates that the voltage regulator is also functioning correctly.

89. Copyright